This invention relates to a device and method by which a human ureter may be made to expand to form what is known as a megaureter. In addition, this invention describes a device which will accomplish this without injury to the kidney.
The term xe2x80x9cmegaureterxe2x80x9d refers to a large, ectatic, dilated ureter, a condition may be congenital or acquired. It is the end result of increased hydrostatic pressure in the ureter from obstruction to the flow of urine, reflux of urine from the bladder back into the ureter (known as vesicoure-teral reflux), or for reasons unknown (i.e., idiopathic). Although megaureter is considered to be a pathologic condition, current medical advances in the field of urinary tract reconstruction have led to the recognition of certain circumstances in which the existence of a megaureter is desirable. A detailed description of urinary tract anatomy and the fundamentals of megaureter may be found in J. N. Kabolin, xe2x80x9cAnatomy of the Retroperitoneum and Kidneyxe2x80x9d, Campbell""s Urology, Ed.6, W. B. Saunders Co., 1992, pp. 3, 36-40 and L. R. King, xe2x80x9cVesicoureteral Reflux, Magaureter, and Ureteral Reimplantationxe2x80x9d, Campbell""s Urology, pp. 1689-1742.
Yearly, several thousand individuals undergo surgical reconstruction of the urinary tract. Reasons for requiring urinary tract reconstruction vary greatly and include: cancers of the urinary tract such as bladder or ureter, congenital defects such as bladder exstrophy, and poorly compliant, small capacity bladders (causing urinary incontinence and renal failure) often seen in paraplegics or patients with posterior urethral valves. The surgical procedures performed vary greatly, though common to all these procedures is the frequent necessity of utilizing segments of the gastrointestinal tract in the reconstructive process.
In the past virtually all segments of the gastrointestinal tract have been used successfully in the reconstruction of the urinary tract. Unfortunately, the incorporation of tissue from the gastrointestinal tract into the urinary tract predisposes the patient to several problems. These problems involve anatomic and physiologic deficiencies of the gastrointestinal tract subsequent to the removal of various lengths of intestine (i.e., malabsorption, diarrhea, and vitamin or bile salt deficiencies). Also, problems inherent in combining the gastrointestinal and urinary tracts include mucous production by intestinal mucosa, enhanced bacterial growth with frequent urinary tract infections, pyelonephritis, abnormal electrolyte and acid reabsorption, urinary stone formation, and occasionally even cancer formation. Further descriptions and fundamentals of urinary tract reconstruction (i.e., urinary diversion and bladder augmentation) can be found in Campbell""s Urology: W. S. McDougal, xe2x80x9cUse of Intestinal Segments in the Urinary Tract: Basic Principlesxe2x80x9d, pp. 2595-2629, and M. E. Mitchell et al., xe2x80x9cAugmentation Cystoplasty Implantation of Artificial Urinary Sphincter in Men and Women and Reconstruction of the Dysfunctional Urinary Tractxe2x80x9d, pp. 2630-2653.
Extensive research has been carried out in an effort to identify an alternative to the gastrointestinal tract in the reconstruction of the urinary system. Ideas have included use of muscle flaps and fascia, harvesting cells of the urinary tract (i.e., urothelium) and cultivating them over bio-absorbable polymers, and transplantation of urothelium from human donors or animals. To date these approaches and others have been seuboptimal.
Recently, however, several medical investigators, have described the use of native urothelium from megaureters to reconstruct the urinary tract (Churchill, B. M., Aliabadi, H., Landau, E. H., McLorie, G. A., Steckler, R. E., McKenna, P. H., Khoury, A. E. xe2x80x9cUreteral Bladder Augmentationxe2x80x9d, Journal of Urology, 150: 716-720, 1993; Hitchcock, R. J., Duffy, P. G., Malone, P. S., xe2x80x9cUreterocystoplasty: The xe2x80x98Bladderxe2x80x99 Augmentation of Choicexe2x80x9d, British Journal of Urology, 73(5): 575-579, 1994). Each of these authors concluded that when possible, bladder augmentation using ureteral tissue from dilated ureters yielded the best outcome, with reduction in the complications common to all reconstructions utilizing the intestinal tract. of course, the feasibility of this operation was contingent upon the patient already having a megaureter. Thus, their experience was restricted to those select patients who, ironically, were xe2x80x9cfortunatexe2x80x9d enough to have the pathologic entity of megaureter. Unfortunately, this represents only a small fraction of the population in need of urinary tract reconstruction. Also, since most of these patients had poorly functioning kidneys associated with megaureter, nephrectomy (i.e., removal of the kidney) or partial nephrectomy (i.e., removal of a portion of the kidney) was performed in the majority of cases reported.
Thus, there is a need to develop a device and method by which a megaureter could be produced in a controlled, monitored setting while maintaining the physiologic integrity of the associated kidney. To date there is no known device or method which will allow a megaureter to be produced iatrogenically without jeopardizing the kidney in a patient requiring urinary tract reconstruction. This could be accomplished with the invention described below which is a method utilizing a ureteral catheter which combines a urinary drainage tube and a tissue expander.
Tissue expanders are reservoirs which can contain varying volumes of either gaseous or liquid materials. Usually constructed of rubber, latex, or silicone elastomers, tissue expanders are extremely pliable, enabling them to be filled to very large volumes while maintaining low pressures within the reservoirs themselves. To date, the most common use of tissue expanders is in the field of plastic surgery, where they are often implanted under the skin and gradually (i.e., over the course of weeks to months) expanded to stretch the overlying skin. Once the tissue is stretched to the desired surface area, the tissue expander may then be deflated and removed. The overlying stretched skin can then be used to cover many types of large wounds ranging from those rendered with the excision of large unsightly scars or tattoos to wounds sustained in avulsion injuries, amputations, or burns.
Tissue expanders differ from the simple xe2x80x9cballoonsxe2x80x9d placed at the ends of conventional urinary catheters (e.g., the xe2x80x9cFoleyxe2x80x9d catheter), which serve the purpose of maintaining a catheter in a certain position or preventing a catheter from becoming dislodged. Also, several ureteral catheters which incorporate balloons are currently in production. For instance, the Microvasive Corporation of Natick, Mass. produces several ureteral dilation products. However, these catheters are not meant to dilate the ureter slowly over several days, weeks, or even months under low pressures (i.e., below diastolic pressure) to achieve large volumes (i.e., three to six hundred milliliters or volumes comparable to normal human bladder capacity) but, rather, are meant to rapidly dilate the ureter to allow stones to pass, rupture strictures in the wall of the ureter, or allow passage of larger bore ureteral instruments. Microvasive""s product catalogues describe the nature of the balloons on the ureteral dilation catheters as xe2x80x9cnoncompliant,xe2x80x9d able to withstand dilation pressures of up to ten or more atmospheres while maintaining balloon diameters ranging from four to ten millimeters.
Tissue expanders have fluid reservoirs which function as carriers of large capacities while maintaining low pressures inside the walls of the reservoirs themselves. This unique property of tissue expanders, which is attributable to the extremely elastic and complaint substance from which they are made (usually silicone elastomer), is an important feature that is crucial in preventing the ischemia and necrosis of surrounding tissue. So unique is this quality of tissue expanders that a multitude of patents have been issued for various tissue expanders and breast protheses. For instance, U.S. Pat. No. 4,217,889 issued Aug. 19, 1980 to Radovan et al. and entitled xe2x80x9cFlap Development Device and Method of Progressively Increasing Skin Areaxe2x80x9d, describes a continuous fluid-tight envelope with a chamber therein . . . whereby the volume of the envelope is determinable as a function of the amount of fluid contained in the chamber . . . xe2x80x9d and xe2x80x9cthe method of progressively enlarging over a prolonged period of time the area of skin and subcutaneous layer overlaying a reference area . . . xe2x80x9d
Another example is U.S. Pat. No. 5,092,348 issued Mar. 3, 1992 to Dubrul et al. and entitled xe2x80x9cTextured Tissue Expanderxe2x80x9d. The abstract states that, xe2x80x9cThe textured surface is expected to decrease subsequent capsular contracture and provide a non-skid surface to hold the device in position and permit differential expansion.xe2x80x9d
Tissue expansion of the ureter has been described in the past (Manders, E. K., et al.) xe2x80x9cElongation of Peripheral Nerve and Viscera Containing Smooth Muscle.xe2x80x9d Clinics in Plastic Surgery, Vol. 13, No. 3, July 1987). This was performed experimentally in dogs by the placement of a rectangular tissue expander posterior and external to the ureter in the retroperitoneal space. This is not practical in clinical practice since placement of a tissue expander external to and behind the ureter would require an extensive open surgical procedure as well as a second operation to remove the apparatus. There is no known research that has ever been performed in the placement and use of a tissue expander inside the lumen of the ureter. Such a device could be installed and removed through the urethra endoscopically or percutaneously via an access tract to the renal pelvis in the patient""s back (i.e., a percutaneous nephrostomy).
The present invention is directed to a device and method by which a megaureter may be produced without compromising the function of the associated kidney. A ureteral catheter for iatrogenically producing a megaureter is comprised of a tissue expander and a drainage tube. The tissue expander comprises a tissue expander conduit with a tissue expander reservoir on the distal end of the conduit and with a first lumen extending from the proximal end of the conduit to inside the reservoir to allow inflation of the reservoir. The drainage tube has a lumen extending at least from the proximal end of the reservoir and out the distal end of the reservoir, the drainage tube lumen having a plurality of holes in its distal end. The reservoir circumferentially surrounds at least a portion of the drainage tube, and the first lumen has an infusion port connected thereto at its proximal end. The excess urothelium produced in the process of tissue expansion can then be used in reconstruction of the urinary tract.